Professor Howard Carmichael
MSc, D.Phil (Waikato), FAPS, FOSA
The Dan Walls Chair in Theoretical Physics
Phone: 64 9 373 7599 X 88899
Research Areas
- Theoretical Quantum Optics
- Quantum Theory of Open Systems
- Quantum Stochastic Processes
Current Research
Quantum Trajectory Theory
Quantum trajectory theory treats the open systems encountered in quantum optics according to a scattering scenario, in which the inputs are classical fields (external fields) and the outputs are classical stochastic processes that model the scattered fields after detection (after their measurement).
The mapping from inputs to outputs is provided by a quantum stochastic process that is set up to account for a particular measurement strategy (e.g., photon counting, homodyne/heterodyne detection, etc.). Both theformal theory and its applications are under study. Recent work includes the development of a novel measurement scheme to correlate the quadrature amplitudes of an electromagnetic field, applications of this scheme in cavity quantum electrodynamics, and the modelling of multimode aspects of collective radiative phenomena (super-radiance).
Entanglement and Correlation in Composite Systems
Quantum optics has traditionally concerned itself with uniquely quantum mechanical aspects of optical phenomena (e.g., photon antibunching and squeezing, violations of Bell inequalities). Attention in recent years has been focused on applications of these quantum features of light to novel schemes for processing information (so-called quantum information science). Entangled states are central to the proposed information processing protocols. Current work is directed towards understanding entangled states, and the contextual correlations they describe, in the broadest sense, i.e.,we are concerned with the physics of composite quantum systems in general. Specific interests include measures of entanglement for open systems, and schemes for the generation and manipulation of this entanglement. Continous variable entanglement is of particular interest. It has been suggested by others that this form of entanglement can be accounted for within stochastic electrodynamics. The suggestion is being assessed. A quantum trajectory theory of continuous variable teleportation is being developed for comparison with the stochastic electrodynamics proposal.
Recent Publications
C. Noh and H. J. Carmichael, "Disentanglement of source and target and the laser quantum state," Phys. Rev. Lett. 100, 120405, 2008.
L. Horvath and H. J. Carmichael, "Effect of atomic beam alignment on photon correlation measurements in cavity QED," Phys. Rev. A 76, 04382, 2007.
F. Dimer., B. Estienne, A. S. Parkins, and H. J. Carmichael, "Proposed realization of the Dicke-model quantum phase transition in an optical cavity QED system," Phys. Rev. A 75, 031804, 2007.
Gu, M., A. S. Parkins, and H. J. Carmichael, 'Entangled-state cycles from conditional quantum evolution," Phys. Rev. A 73, 043813, 2006.
H. Nha and H. J. Carmichael, "Distinguishing two single-mode Gaussian states by homodyne detection: An information-theoretic approach," Phys. Rev. A 71, 032336, 2005.
H. Nha and H. J. Carmichael, "Decoherence of a two-state atom driven by coherent light," Phys. Rev. A 71, 013805, 2005.
H. Nha and H. J. Carmichael, "Entanglement within the quantum trajectory description of open quantum systems," Phys. Rev. Lett. 93, 120408, 2004.
H. Nha and H. J. Carmichael, "Proposed test of nonlocality for continuous variables," Phys. Rev. Lett. 93, 020401, 2004.
J. P. Clemens and H. J. Carmichael, "Shot-to-shot fluctuations in the directed superradiant emission from extended atomic samples,"J. Opt. B 6, S736, 2004.
H. J. Carmichael and H. Nha, "Vacuum fluctuations and conditional homodyne detection of squeezed light," J. Opt. B 6, S645, 2004.
Books
H. J. Carmichael, Statistical Methods in Quantum Optics 2: Non-classical Fields, Springer-Verlag, Berlin, 2008.
H.J. Carmichael, Statistical Methods in Quantum Optics 1: Master Equations and Fokker-Planck Equations (Springer, Berlin, 1999)
H.J. Carmichael, An Open Systems Approach to Quantum Optics, Lecture Notes in Physics, New Series m -- Monographs, Vol. m18 (Springer, Berlin, 1993)
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